上海科技大学知识管理系统

The recent discovery of intrinsic ferromagnetic order in the atomically thin van der Waals crystal CrXTe3 (X = Si, Ge) stimulates intensive studies on the nature of low-dimensional magnetism because the presence of long-range magnetic order in two-dimensional systems with continuous symmetry is strictly prohibited by thermal fluctuations. By combining advanced many-body calculations with angle-resolved photoemission spectroscopy we investigate CrSiTe3 single crystals and unveil the pivotal role played by the strong electronic correlations at both high- and low-temperature regimes. Above the Curie temperature (T-c), Coulomb repulsion (U) drives the system into a charge transfer insulating phase. In contrast, below T-c the crystal field arranges the Cr-3d orbitals such that the ferromagnetic superexchange profits, giving rise to the bulk ferromagnetic ground state with which the electronic correlations compete. The excellent agreement between theory and experiment establishes CrSiTe3 as a prototype low-dimensional crystal with the cooperation and interplay of electronic correlation and ferromagnetism.